This research is designed to clarify the role played in the neural control of feeding by afferent, efferent and internuncial mechanisms at various levels of the avian brain. As a first step, studies of the spatio-temporal organization of eating have been carried out using high speed cinematography in order to clarify the sensory determinants of the behavior. The patterning of individual feeding responses into feeding bouts under the control of sensory and motivational variables has been studied under both long and short term conditions. Anatomical and electrophysiological procedures have been used to define and characterize a network of structures involved in the control of feeding and neurobehavioral studies have served to clarify their functional contribution to feeding behavior. These studies have implicated the trigeminal system in the neural control of avian feeding behavior and comparative studies have confirmed that this system plays a similar role in the control of mammalian ingestive behavior. Future studies are designed to clarify the efferent mechanisms controlling feeding in the pigeon, taking as a behavioral starting point the grasping response used in eating. The central representation of the avian beak muscles will be determined using anatomical marker techniques (HRP) and similar techniques will be used to clarify descending pathways related to final common path mechanisms for beak movements. Behavioral testing procedure will be used to bring "grasping" behavior under experimental control and analyse both its visual and somatosensorimotor control. Neurobehavioral procedures will be used to identify neural structures involved in the efferent control of feeding and characterize their role in this behavior. Analysis of the neural control of feeding in the pigeon is intended to serve as a "model system" for the study of vertebrate ingestive behavior. It is also expected to provide data on neural control of operant and autoshaped responses, visuomotor mechanisms and behavioral final common path mechanisms.